This invention is directed to a solventless sealant composition, two-component, for use in pneumatic tires containing an air-retaining liner forming an integral part of said tire and for use in inner tubes contained within a tire casing. The sealant composition is applied to the inside of such a tire to function with the integral air-retaining liner to seal any hole that may be formed in said liner by a piercing object, such as a nail. When injected into an inner tube contained within a tire casing, the sealant composition becomes uniformly distributed therein on rotation of the tire.